Twenty-six foreigners from 17 countries are among the 30 people who were arrested on the Greenpeace icebreaker, Arctic Sunrise, after a protest in which they tried to scale Russia's first offshore oil platform.

They face up to seven years in prison on hooliganism charges, but were released on bail last month by courts in St Petersburg and had hoped to be able to go home.

Among them is 59-year-old Tasmanian man Colin Russell, who was reunited with his family who flew to meet him in St Petersburg upon his release last month.

Greenpeace says one of the activists has received a letter from Russia's federal Investigative Committee, saying it will not seek exit visas for the non-Russians.

The committee "has written to one of the 30 - Anne Mie Jensen of Denmark - indicating that they are not free to leave the country," the Netherlands-based environmental group said in a statement.

"Lawyers for Greenpeace expect all of the non-Russian defendants to be treated in the same way by the authorities, meaning they would now be forced to stay in St Petersburg for Christmas and possibly well beyond," it said.

Russia's Federal Migration Service has said it will not issue visas until it receives a direct request from the Investigative Committee.

The Investigative Committee declined immediate comment.

Greenpeace says the Arctic protest was peaceful and the charges are unfounded.

The arrest of the activists, who were held in jail for two months and initially risked up to 15 years in prison on piracy charges, has drawn criticism from the West.

The United Nations maritime tribunal ruled on November 22 that the Greenpeace ship and its crew must be allowed to leave Russia, but Moscow declined to take part in the case lodged by the Netherlands and has suggested it would defy the ruling.

Moscow says the activists endangered lives and property in the protest at the state-controlled energy giant Gazprom's Prirazlomnaya platform in the Pechora Sea, a key element of Russia's plans to develop the Arctic.

The foreign activists also include citizens of Argentina, Brazil, Britain, Canada, Denmark, France, Finland, Italy, the Netherlands, New Zealand, Poland, Sweden, Switzerland, Turkey, Ukraine and the United States.